How is aluminum sorted

Sorting of aluminum scrap
Laser checks the elements

The Cologne-based sorting specialist Steinert is closing a gap with the first LIBS sorting system in Europe.
In order to return aluminum to recycling loops, pure fractions are required, which processors can only produce step by step. The first step in the recycling process is the separation of ferrous and non-ferrous metals - both possible with magnetic separation technology. In the next step, the key technology is used: X-ray transmission separates heavy from light metals and produces defined aluminum mixtures. The Steinert XSS T has proven itself in this for years and is state of the art worldwide.
In the meantime, the combination of several sensors with X-ray transmission technology in the form of Steinert KSS is in demand in order to achieve even more sorting depth. It is a platform on which various sensors are used: 3D, color and induction detection. A fourth sensor can also be added to the system (near-infrared, X-ray transmission or X-ray fluorescence sensor). For the preparation of the Zorba fraction - the mixture of light and heavy metals - materials are separated e.g. by means of X-ray technology.
The missing link for aluminum recyclers that separates pre-sorted aluminum scrap according to its alloys has passed its baptism of fire in practice: With the specially designed line sorting system Steinert LSS, the customer is able to separate several alloys with just one detection by the LIBS sensor . LIBS - short for Laser-Induced Breakdown Spectroscopy - is a technology for element analysis. The calibration methods stored in the measuring device analyze the concentrations for the alloying elements Cu, Fe, Mg, Mn, Si, Zn and Cr as standard. The sorting task with alloys is to first separate the comminuted material mixture in order to always lead the material past the laser in such a way that the laser pulses hit the surface of the material. Tiny material particles evaporate in the process. The emitted energy spectrum is recorded and analyzed simultaneously so that the alloy and the individual alloy components of each individual object can be recognized. Detected in the first part of the machine, compressed air nozzles shoot the up to seven different materials in the second part of the machine into different bunkers, depending on the composition of the elements. “The demand for this sorting method, which is up to 99.9% accurate, is increasing - the next orders are already recorded in the order books,” reports Technical Director Uwe Habich.

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